Submission #813116

#	Time	Username	Problem	Language	Result	Execution time	Memory
813116		Theo830	Flight to the Ford (BOI22_communication)	C++17	0 / 100	302 ms	200 KiB

communication

#include"communication.h"
#include <bits/stdc++.h>
using namespace std;
const int bits = 30;
void encode(int n, int x){
    vector<int>arr;
    set<int>pos;
    for(int j = 0;j < bits;j++){
        pos.insert(j);
        if(x & (1<<j)){
            arr.push_back(1);
        }
        else{
            arr.push_back(0);
        }
    }
    while(pos.size() > 1){
        auto it = pos.begin();
        auto it2 = pos.begin();
        it2++;
        int i = (*it),j = (*it2);
        int a = send(arr[i]);
        int b = send(arr[j]);
        int c = send(arr[j]);
        int d = send(arr[i]);
        if(b == c){
            pos.erase(j);
        }
        else{
            pos.erase(i);
        }
    }
}
void dfs(int idx,int cur,vector<int>&arr,vector<vector<pair<int,int> > >&adj){
    arr[idx] = cur;
    for(auto x:adj[idx]){
        dfs(x.first,cur ^ x.second,arr,adj);
    }
}
pair<int, int> decode(int n){
    int A = 0,B = 0;
    vector<vector<pair<int,int> > >adj;
    vector<int>arr;
    adj.assign(bits+5,vector<pair<int,int> >());
    set<int>pos;
    for(int j = 0;j < bits;j++){
        pos.insert(j);
    }
    arr.assign(bits,-1);
    while(pos.size() > 1){
        auto it = pos.begin();
        auto it2 = pos.begin();
        it2++;
        int i = (*it),j = (*it2);
        int a = receive();
        int b = receive();
        int c = receive();
        int d = receive();
        if(b == c){
            arr[j] = b;
            pos.erase(j);
        }
        else if(a == d){
            arr[i] = a;
            pos.erase(i);
        }
        else{
            adj[j].push_back({i,a ^ c});
            pos.erase(i);
        }
    }
    auto it = pos.begin();
    int i = (*it);
    dfs(i,0,arr,adj);
    for(int j = 0;j < bits;j++){
        if(arr[j]){
            A += (1<<j);
        }
    }
    dfs(i,1,arr,adj);
    for(int j = 0;j < bits;j++){
        if(arr[j]){
            B += (1<<j);
        }
    }
    A = max(1,A);
    B = max(1,B);
    B = min(n,B);
    A = min(n,A);
    return {A,B};
}

Compilation message (stderr)

communication.cpp: In function 'void encode(int, int)':
communication.cpp:22:13: warning: unused variable 'a' [-Wunused-variable]
   22 |         int a = send(arr[i]);
      |             ^
communication.cpp:25:13: warning: unused variable 'd' [-Wunused-variable]
   25 |         int d = send(arr[i]);
      |             ^

• Subtask 1: 0 / 15
• Subtask 2: 0 / 85